Abstract: In view of the difficulties existing in the accurate identification of structures’ modal parameters, a modal parameter identification method based on local mean decomposition (LMD) and band-pass filtering (BPF) was proposed. Firstly, the LMD method was used in the decomposition of a displacement simulation signal and a frequency measuring signal of a compressor guide vane, and modal aliasing phenomenon existed in the decomposed PF components; Then, the LMD-BPF method was utilized in the decomposition of the displacement simulation signal and frequency testing signal of the guide vane, and each modal frequency was accurately and successfully separated; Finally, the LMD-BPF modal parameter identification method was employed to identify the modal parameters of the displacement simulation signal and frequency testing signal of the guide vane. The maximum errors between the four modal frequencies and damping ratios of the identified displacement simulation signal and the corresponding theoretical values were 0.205% and 2.387%, respectively. The maximum difference between the three modal frequencies of the identified guide vane and the testing frequencies was less than 1.0%, and the maximum difference between the three modal damping ratios of the identified guide vane and those identified by half power bandwidth method was less than 0.65%. The simulation analysis and experimental study of modal parameter identification verified the validity of the proposed method.

Key words: modal parameter identification, local mean decomposition, band-pass filtering, compressor guide vane